A new chemical approach to optimize the in vitro SPF method on the HD6 PMMA plate.

In a previous study, we demonstrated that control of the roughness of molded PMMA plates improves in vitro SPF reproducibility. However, in vitro/vivo deviations are still observed. Sunscreens show different behavior during spreading on the HD6 surface according to the formulation, resulting in a more or less homogenous distribution.

Predicting the efficacy of sunscreens in vivo veritas.

A novel in vitro technique for measuring the efficacy of sunscreens over the skin surface is described. It is demonstrated that those products that spread easily are associated with both a low variance in delivered SPF and a subjective assessment of a product that is pleasing to use, which in turn results in a higher application thicknesses and greater delivered photoprotection leading to improved health benefits of sunscreen use.

Sunscreen in vitro spectroscopy: application to UVA protection assessment and correlation with in vivo persistent pigment darkening.

In the present study, we have described an in vitro spectroscopic method to evaluate the sunscreen products for UVA sun protection factor. The roughened PMMA plates have been used as a transparent substrate on to which the test product is spread. The UVA protection factors have been deduced from the UV-transmittance data measured in the UVA area.

Efficiency of a continuous height distribution model of sunscreen film geometry to predict a realistic sun protection factor.

Irregularities in the geometry of sunscreen films spread on rough areas, like skin, is often presented as being the main cause of the degree of UV absorption achieved by the UV filters that are inside. Until now, only the step film, a model invented by O'Neill, was simple enough to calculate UV data close to in vitro experimental data, after determination of a limited number of fraction areas with their corresponding thickness. However, such models are obviously too simple to represent a real situation.